Flying Submarine whistles over treetops frightening three teenage witnesses in Alvin, Texas then shoots off and vanishes

The three witnesses were outside when they heard a loud whistle and humming sound. They looked up and saw a craft that resembled a "flying submarine" with three lights on it (red in front, then green, then blue all in a line on the right side). It appeared right over their heads just above the tree line by the house they were at, and it followed the driveway down to the next tree line whereupon it suddenly shot off upwards and to the right and quickly disappeared towards the moon (NE) which was close to being full. The object was charcoal grey color in the dark night sky. THe three lights on the object were blinking rapidly like a stobe. All of the witnesses were frightened by the experience. They include a recent high school graduate (18) and two females (17 and 15). They immediately notified me (stepfather to one of the witnesses). There is a slight possibility of about 20 minutes of missing time but not all of them can agree on this.